Lamp



April 3o, 1940.

C. M. STITT LAMP Filed Aug. '7. 1937 2 Sheets-Sheet l 'Illlll/ April 3o,1940. C, M ST." 2,199,014

l LAMP Filed Aug. '7, 1937 Q 2 Sheets-Sheet 2 ma ,a

l VVshown in Figs. and 6;

Patented Apr. 30, 1940 elaine Monroe stm. Hmmm, onu. Application Augusta1931, serial No. 151,902

2 Claims.

- This invention relatesto lamps and more particularly pertains toelectric lamps of the Vcharacter employed in the production'oiilluminating beams, flood lights, and other illuminators 'for producingwhite light or lsubstantially white light. v .v An object of theinvention is `to provide 'a lamp which is especially applicable for useas a head light for vehicles where it is desired to obtain eirectiveillumination without excessive glare.

Another object is to 4provide a lamp which, while projecting a beam ofwhite or near white iight, is so constructed and operated that whenviewed from the front thereof and proximate thereto and particularlyfrom points forward of but to either side thereof will present to theobserver an illuminated eld comprising areas cornposed of a plurality ofcolors andwith `the absence of blinding glare, but which when viewedfrom points remote from the lamp will appear as a white or nea-r' whitelight free'of excessive glare.

A further object is to provide a lamp of the above character which issimple in construction and in which the parts may be readily assembled.'

With the foregoing objects in view, together with such other objects andadvantages as may subsequently appear, the invention is carried intoeiiectas illustrated by way of example in the accompanying drawings inwhich:

Fig. 1 is aperspective, view of the lamp as viewed from the front and toone side thereof;

Fig.' 2.is a detail in vertical section of the lamp with parts ofthe-housing broken away;

Figg is a detail in elevation as viewed on the line 3 3 of 1ig.2;

Fig. 4 is a sectional view as seen v 'on menne 4--4 africa;

' Fig. 5 is a diagrammatic viewv inv elevation 'of one form of colorscreen employed in the lamp; Fig. -6 is a viewin side elevation of thescreen shown in'Fig. 5;`

Fig. 'I is a perspective view of one -of "the screen segmentsv employedin 'the' construction Fig. 8 is a view'in elevation of the front ofthelamp shown in Fig'. 42 with the colvervlens removed showing another formof the screen;

Fig. 9 isa diagram in perspective` depicting the mode of operation ofthe invention.v

Referring to thej drawings more specifically, A indicates generally 'alamp housing having an openend fitted with a reflector B having fa rimVIII which seats on an internalshoulder' Il on the housing. Thereflector may be of any; suitable type; being here shown as comprisingthe ordinary parabolic reiiector employed in 'motor v ehicle head lightshavingk a central sleeve Il'car4 f5 rying a socket il. An electric lampC fitted with an illuminating filament il is niounted'inthe socket andis adapted to be adjusted tof proper focus by shifting the socket I3longitudinally'in thesleeve l2." 'V

While various types .of lamps may be employed as a source of lightorlight aenerating means I have found that highly satisfactory 'resultsare obtained by the use of an electric lamp having a glass bulb formedwith a transparent I5 area' I5 on its outer end wall iv and'ha'vingltranslucentsidewallsl.

` A color screen D is'disposed across the reflector B. in front of thelamp C which screen 'embodies at least three sectioned, b,'and"c formed20 Ito transmit light rays lof different colors'such as red, violet andgreen respectively; so as rto propagate red, violet and green rays whichwhen co-mingled with and superimposed upon each other will produce abeam of white or near white light. I

Theformation ofthe sections a, b and c to have the desired colorscreening and colored ray producing properties `may be eiected eitherbyforming the sections of glassA embodying the requisite pigmentation, orby the employment ofany other transparent or translucentsheet'materialsuch as the `phenol-resin products orfCellonhane and similarmaterialsforby the use of transparent or translucent Ymaterial appliedupon plates of y The sections a, b, and c, maybe formed in one piece ormay comprisevsepa'rate segments'. vWhere 'segmental` sections areemployed as shown in Figs." `2, 3,4; and 8-they areucarried oninter'con-40 nected 'radiating channeledfmmbers 6, j, and if linterposedv betweenthe 'contiguous edges of the segmental sections with A the'f latterfse.ted in the channels thereof as particularly showniin Fig. 4.

The outer ends'jof themeinbers enff; 'a'ndig arev45 formed with tonguesl1 'which qverlithefmargini0 of the reflector Bi'a'nd' are engagedAcollectively with the latter-Lto theshoulder I'I by f screws *IlPreferably convexoconcave "l with fthe -margirr-V of its concave vfaire4opposite and concentric xwith .the weer. rae. E ...Sea-is, 455

2l having an inturned marginal flange 2i en-A gageable with the rim ofthe lens. The lens E is transparent but is preferably formed with atranslucent marginal portion 22.

Interposed between the screen D and the lamp C is a concave reflector Fwhich overlies the transparent outer end portion Il of the lamp bulb inslightly spaced relation thereto and which reflector F connected to theinterconnected portion of the members e, j and g by a screw 22 whichpasses through the intersecting portion of the members and is threadedinto engagement with a hub 24 on the reflector. The purpose of thereflector F is to direct rays emitted from the transparent end II of thelamp bulb back through the translucent wall It thereof so as to augmentthe intensity of the light beam projected by the reflector B.

The reflectors B and F and the lens E are disposed with their principalaxes in axial alignment with each other and with the center of thefilament I4, and the color screen segments a, b and c extend radiallyfrom the axial line of the reflector.

The color screen sections a, b and c are formed of practicallycorresponding light absorptive properties so that the intensity of lightpropagated by the sections will be equal or atleast nearly equal.

In the operation of the invention as illustrated in Figs. 2 and 9 onilluminating the lamp C by directing electrical current through thefilament Il, a portion of the resultant rays pass directly through thetranslucent side wall I6 of the lamp bulb, while another portion of therays pass through the transparent end portion l5 Aof the bulb and arereflected by the reflector F back through thetranslucent wall I6 of thebulb. In this fashion all the rays emitted from the lamp are scatteredand diffused and directed against the reflector B so as to be'reflected. in most part by the latter and directed through thescreens a,b and c and through thel refraction lens E thus propagating a beam oflight which diverges according to the designed contours of the reflectorB and lens E.

By disposing the lamp C in proper focal posi- ,tion relative to thereflector B the propagated beam, by reason of its being composed of red,violet and green rays superimposed and comingied, will be white or nearwhite, and will effect illumination of bodies accordingly.

Inasmuch as it is diilicult to form the reflector B as to avoid theformation of a. fringe of colored rays around the major beam, suchfringe is eliminated at least in most part by the provision of theformation of the translucent margin 22 on the lens E which acts toscatter and diffuse the color rays of the fringe.

In the modified form of the color screen shown in Figs. 5, 6 and 7, thesegments a, b and c are prismatic so as to effect refraction of thescreened rays in a fashion yto cause superimposing of the groups of rayspropagated by the several segments and thereby produce the desired whiteor near white light free of excessive glare. By thus forming the screensegments to have the refractive properties of prisms they may beemployed either with or without a supplemental refracting lens E.

An important feature of the invention resides in the fact that whiieabeam of light is propagated to produce sight sensation of whiteness whenviewing a bodyonwhich the beam is incident, the rays emitted from thelamp incident on the retina of the eye produce color sensations so thata person viewing the lamp from the front or diagonally from the frontthereof will discern within limits the luminous colored segments a, band c. In other words, -an observer lviewing the illuminated lamp willobserve the luminous red, violet and green segments a, b and c free ofblinding glare. However, such condition prevails within limits ofdistance or server and the lamp the 'color sensations developwithgradually increasing intensity to a maximum at close proximity to thelamp.

In order to produce a beam of white or near white light by means of thepresent invention it is essential that the color screen sectionscollectively transmit light of various wave lengths ranging from low tohigh value, and accordingly it is necessary that the screen include atleast one red section for propagation of light of long wave length, atleast one violet section for propagation of lightl of short wave length,and at least one section capable oi propagating light of intermediatewave lengths, which latter section is preferably green since ittransmits composite rays of intermediate wave lengths. It ismanifest,however, that in some instances it may be desirable to produce a beamwhich is slightly tinged with color, such'as to have, for example, areddish-yellow tinge,' or greenish tinge, or blue- Vish tinge, in-whichevent the color screen will be formed with a section or sections of acharacter to aord the desired excess of color constitutent, as byvarying the shade of the green section to render it capable oftransmitting an excess of yellow rays, or an excess of blue rays.

Where it is desired to produce a beam which is clear white or having ablueish tinge, it is necessary that the source of light C be clearwhite, that is, one which emits light containing waves of all wavelengths with their relative intensity such that the color sensationproduced by their incidence on the retina is that of whiteness. However,though electrically operated filament or glow lamps are defective inblue, such does not preclude their .use in my lamp, since suchdeilciencydoes not suillciently detract from the whiteness of the beam as toaffect the practicability of the lamp for general purposes ofillumination, as for example in the head lights of vehicles, and floodlights on aircraft landing fields, and in general for any transmittedlight of whatever character or purpose as may be required.

While I have set forth specific embodiments of my invention I do notlimit myself to the constructions shown, and-the invention embraces suchmodifications asy come within the purview of the accompanying claims.For example, while I have shown the lamp as equipped with a refractingcover lens E there are occasions where such lens may be disp'ensed withit having been found in practice that in applying the lamps asheadlights for a vehicle sumcient intermingling of the colored rays asdirected through the screens a, b and c is eifected as to produceasatisfactory beam of the character set forth.

I claim:

Atransparent end `wall portion, a color screen ad- I 1. In a lamp. anelectric nlament lamp including a bulb having a translucent side wallportion and a transparent end wall portion, a'

color screen adjacent said electric lamp extend- '5' ing in front of thetransparent end wall portion thereof, said color screen embodying aplurality of segmental sections of different colors including a redsection. a violet section and a section for transmitting light raysintermediate 10. red and violet rays; a renector for projecting lightemanating from said electric lamp through said screen, a secondreflector extending over the transparent end portion of said bulb forreiiecting rays from said electric lamp onto said ll ilrst namedreilector through the translucent side walls of said bulb, a reiractinglens extending over said screen, said refracting lens and first namedreflector cooperating to eilect superimposition and commingling ofcolored rays emit- I) ted from said screen to produce a white ornearwhite illumination. and means on said retracting lens for diffusingfringe rays.

2. In a lamp, the combination of an electric ilJament lamp including abulb having a trans- I lucent light diffusing side wall portion and ajacent said electric lamp extending in front of the transparent end wallportion thereof, said color screen embodying a plurality of sections ofdifferent colors including a red section, a violet section and a sectionfor transmitting light rays intermediate red and violet rays; saidscreen sections having similar or like light absorptive properties topropagate rays oi' similar or like intensity; a parabolic reflectorencompassing said bulb and arranged to project light emanating from saidbulb co/inciden'tly through the several sections-of said screen to forma beam, a

second reflector extending over the transparent end portion of said bulbarranged to reect rays emitted from the outer end of said electric bulbback ontov said iirst named reiiector through the translucent side wallsof said bulb, and a reiracting lensextending over said screencooperating with said ilrst named reflector to effect superimpositionand commingling of colored rays emitted from said screen to produce awhite or near white illumination.

CHARLES MONROE S'ITIT.

